1. Field of the Invention
The invention relates to a circuit board; more particularly, the invention relates to a circuit layout structure suitable for a circuit board to reduce signal interference, a circuit board having the circuit layout structure, and an electronic assembly having the circuit layout structure.
2. Description of Related Art
At present, the USB 3.0 has become a very popular standard, whereas issues of electromagnetic interference (EMI)/radio frequency interference (RFI) may arise at the frequency of approximately 2.5 GHz. Since the data rate and the clock frequency of the USB 3.0 standard are 5 Gbps and 2.5 GHz, respectively, devices (e.g., a wireless module of a wireless mouse) with the operating frequency at approximately 2.5 GHz may be interfered by USB 3.0 signals and may fail to work.
For instance, a USB 3.0 hub has a circuit board, a USB 3.0 chip, and a USB 3.0 electrical connector. The USB 3.0 chip and the USB 3.0 electrical connector are installed on the circuit board, and the USB 3.0 chip is often electrically connected to the USB 3.0 electrical connector through surface circuits of the circuit board. If the casing of the USB 3.0 hub is made of plastic and is not covered by appropriate metal materials, the frequency of RFI from the USB 3.0 signals (with the clock frequency at 2.5 GHz) transmitted through the surface circuits of the circuit board is approximately at 2.5 GHz. Such EMI/RFI may pose an impact on the wireless module of the wireless mouse with the operating frequency at approximately 2.4 GHz.